Though we always have other instruments on our mind, the ToneWoodAmp has been developed and tested primarily for the acoustic guitar.
The current version of ToneWoodAmp is recommended for steel and nylon string acoustic guitars including resonator guitars, Weissenborn guitars and even dobros. ToneWoodAmp works well with acoustic bass guitar as well.
We've also seen customers install TWA on resonator back banjos and ukuleles (although the small soundhole may add considerable difficulty to install).
We are planning to make the ToneWoodAmp available for other instruments in the future.